Communications
6.2 PtP, USS, and Modbus communication protocols
Easy Book
Manual, 05/2009, A5E02486774-01
77
6.2.1 PtP instructions
The PORT_CFG, SEND_CFG, and RCV_CFG instructions allow
you to change the configuration from your user program.
• PORT_CFG changes the port parameters such as baud rate.
• SEND_CFG changes the configuration of serial transmission
parameters.
• RCV_CFG changes the configuration of serial receiver
parameters in a communication port. This instruction
configures the conditions that signal the start and end of a
received message. Messages that satisfy these conditions
will be received by the RCV_PTP instruction.
The dynamic configuration changes
are not permanently stored in the
CPU. After a power cycle, the initial
static configuration from the device
configuration will be used.
The SEND_PTP, RCV_PTP, and RCV_RST instructions control
the PtP communication:
• SEND_PTP transfers the specified buffer to the CM module.
The CPU continues to execute the user program while the
module sends the data at the specified baud rate.
• RCV_PTP checks for messages that have been received in
the CM module. If a message is available, it will be
transferred from the CM to the CPU.
• The RCV_RST resets the receive buffer.
Each CM module can buffer up to a maximum of 1K bytes. This
buffer can be allocated across multiple received messages.
The SGN_SET and SGN_GET are
valid only for the RS232 CM
module. Use these instructions to
read or set the RS232
communication signals.
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